Artificial nail covering and method of preparing the same



March 24, 1970 s. JARBY 3,502,088

ARTIFICIAL NAIL COVERING AND METHOD OF PREPARING THE SAME Filed June 21, 1966 I N VEN TOR. SVEN JARBY BY Kw KIM AGENT United States Patent 3,502,088 ARTIFICIAL NAIL COVERING AND METHOD OF PREPARING THE SAME Sven .Iarby, Salez, Saint Gall, Switzerland, assignor to Inter-Taylor AG., Chur, Switzerland Filed June 21, 1966, Ser. No. 559,307 Claims priority, application Denmark, June 22, 1965, 3,159/ 65; Feb. 9, 1966, 676/66 Int. Cl. A45d 29/00 US. Cl. 132-73 9 Claims ABSTRACT OF THE DISCLOSURE A set of components for forming an artificial finger nail consists of a plastic nail blank having an inner face concavely curved in three dimensions and a paste like adhesive having an acrylic monomer base. An oxidizing catalyst which is not initially present in the adhesive is provided either as a coating on the concave blank face or in a separate lacquer component of the set. The separate catalyst lacquer is applied to a digit and followed by the adhesive and the nail blank.

This invention relates to cosmetic compositions and their use, and particularly to an artificial nail covering.

It is common practice to cover nails on digits, that is, fingers or toes, with artificial shields shaped and constructed to simulate nails of better appearance than the natural nail. An artificial nail blank is attached to the digit or to the natural nail mechanically by small fasteners or adhesively by a bonding layer which engages the inner face of the nail blank.

The known mechanical fasteners do not hold the nail blank with sufficient force to withstand stresses encountered in normal use of a hand or foot. The bonding agents heretofore employed in this art do not combine the properties desirable in such a material in a satisfactory manner.

The object of the invention is the provision of a decorative nail covering in which an artificial blank is attached to a digit by a bonding agent having high mechanical bonding strength and good resistance to water, aqueous detergent solutions, and other media with which the hands or feet of a wearer may normally be expected to come in contact.

It is another object of the invention to provide a bonding agent for a nail covering which hardens rapidly after application even when separated from the ambient atmosphere by an impervious nail blank.

A further object is the avoidance of contact between the nail bed or other body surfaces and materials in the nail covering which may irritate body tissues.

An additional object is the provision of a set of materials from which even a person lacking manual dexterity can form a nail covering very rapidly and easily.

With these and other objects in view, the invention, in one of its aspects, resides in a two-component set of materials. One component is a nail blank, an elongated thin sheet of resilient solid material, whose outer and inner faces are curved in two planes perpendicular to each other, the inner face being concave and provided with an oxidizing catalyst. The other component is a bonding agent for adhesively bonding the inner face of the blank to the digit to be covered. The bonding agent of the invention is a paste-like adhesive mass which is free from volatile solvents and responds to contact with the catalyst on the inner face of the blank by curing and thereby adhering to the inner face as Well as to the digit, more particularly to the natural nail of the latter.

In using this set of materials a layer of the adhesive mass is applied to the tip of a finger or toe, the inner 3,502,088 Patented Mar. 24, 1970 face of the nail blank is coated with adhesive unless this has been done previously in the manufacture of the blank, and the coated face of the blank is pressed against the adhesive layer on the digit. The adhesive material of the preferred adhesive composition of this invention contains a liquid, polymerizable organic monomer which is polymerized to a solid by contact with the catalyst on the nail blank at body temperature or even at the somewhat lower temperatures which may prevail at the exposed ti of the treated digit. The adhesive layer is thereby hardened.

Additional objects, features, and advantages of this invention will become apparent from the following detailed description of preferred embodiments of the invention as illustrated in the accompanying drawing in which:

FIG. 1 shows a finger tip provided with an artificial nail covering of the invention in side elevation, and partly in section on line II in FIG. 2; and

FIG. 2 shows the finger tip in plan view.

Referring now to the drawing in detail, there is seen a finger tip 1 carrying its natural nail 2. A layer of cured bonding agent 3 covers the nail 2 and extends to the nail fold 4. The layer 3 is covered, though not completely, by a thin, shape retaining, artificial nail blank 5 which is of arcuate contour not only in the longitudinal median plane of the blank, as shown in FIG. 1, but also in all planes perpendicular to the plane of FIG. 1 and to the direction of elongation of the nail blank 5, as is evident from FIG. 2.

The blank 5 is a resilient molded sheet of thermoplastic synthetic polymer resin containing minor amounts of plasticizer, if needed, and coloring agents, if so desired. The plasticizer and coloring agents, if any, are added to the resin prior to molding so that they are uniformly distributed in the nail blank 5 from the convex outer face to the concave inner face.

The radii of curvature of the concave face are smaller than those of the corresponding sections of the natural nail 2 so that the latter and the nail blank 5 enclose a space whose thickness decreases from the center toward the nail fold 4 as best seen in FIG. 1. The space is completely filled with cured bonding agent 3. An additional amount of the bonding agent extends in a U-shape along the nail fold 4 as is evident from FIG. 2.

The preferred materials for the nail blank 5 are resin compositions consisting mainly of polycarbonates or of acrylic polymers, polymethyl methacrylate having particularly desirable optical, mechanical and chemical properties. It may be replaced, at least in part, by polymerized other lower alkyl esters of acrylic and methacylic acid, by polyacrylonitrile, and by polymethacrylonitrile. Many other materials are suitable for use as nail blanks, and will readily suggest themselves to those skilled in the art.

In forming the artificial nail covering shown in the drawing, a protective lacquer may first be applied to the finger tip, that is, to the exposed faceof the nail 2 and to the nail fold 4 where it is expected to make contact with the bonding agent 3. The lacquer is permitted to dry, and is too thin when dired to be visible on the scale of FIG. 1. It may contain a catalyst for curing the bonding agent.

The inner face of the nail blank 5 is coated with the same catalyst-bearing lacquer, or catalyst may be applied to the blank 5 in any other manner. A layer of the bonding agent 3, which is originally a plastically deformable paste, is applied next to the finger tip 1 over the protective lacquer layer or directly to the nail 3 and other portions of the finger when a protective lacquer is not employed. The inner face of the nail blank 5 is pressed against the layer of bonding agent so that air is displaced from the space between the adhesive mass and the nail blank. If the amount of bonding agent applied was greater than needed to fill the space between the blank and the 3 finger tip, the excess is extruded along the edges of the blank.

The blank illustrated in the drawing is somewhat undersized, that is, it does not quite. cover the nail 3. The extruded portion of the bonding agent covers the remainder of the nail 3, and may be trimmed as needed. The catalyst in the protective lacquer or on the underside of the nail blank dilfuses into the bonding agent and causes the same to cure rapidly.

The following examples further illustrate the invention, but it will be understood that the invention is not limited thereto.

EXAMPLE 1 An adhesive paste was prepared by mixing the following ingredients:

Parts by weight Polymethyl methacrylate 20 Methyl methacrylate 20 N,N-dimethyl-p-toluidine 0.4 Titanium dioxide 0.2

I-Iydroquinone 0.02

It was applied to a finger nail over a protective lacquer originally consisting of Polymethyl methacrylate 5 Benzoyl peroxide 2.5 Dibutyl phthalate 2.5 Methylethylketone 25 The methylethylketone rapidly evaporated so that the adhesive paste could be. applied without an intentional waiting period. The benzoyl peroxide in cooperation with the N,N-dimethyl-p-toluidine caused rapid polymerization of the monomeric methyl methacrylate in the paste, and hardening of the paste. Before the paste was more than partly cured, a nail blank consisting entirely of polycarbonate resin and having the shape shown in the drawing was pressed against the adhesive mass and was held fast at once. The strength of the bond increased in the few additional minutes required for substantially completely curing the paste, and was thereafter sufiicient to prevent separation of the blank from the natural nail by reasonable mechanical forces, such as those a natural finger nail is expected to withstand. The artificial nail covering was not loosened when the wearer took a bath or immersed the hands in warm water containing a strong dishwashing or laundering detergent.

Even better bonding between the polycarbonate nail blank and the. finger tip was achieved when the procedure was repeated as described above, but the inner face of the nail blank was coated with the lacquer containing benzoyl peroxide containing polymethyl methacrylate as the film forming component before it was pressed against the adhesive mass.

Under otherwise identical conditions, a nail blank consisting mainly of polymethyl methacrylate was more strongly bonded to the finger tip by the afore-described adhesive paste than the polycarbonate blank because the identical polymers in the blank and in the paste were integrally bonded to each other after curing of the paste. A distinct phase boundary between the materials of the nail blank and of the cured adhesive mass could not be found under the microscope in the sectioned nail covermg.

A small amount of pigments or other coloring matter admixed to the resin from which the nail blank was molded did not have a measurable effect on the bond between the blank and the finger tip.

EXAMPLE 2 A nail blank having the shape shown in the drawing was made from polycarbonate resin by injection molding. Its inner face was coated with a lacquer prepared from 5 parts each of benzoyl peroxide and polymethyl methacrylate, and 2.5 parts methylethyl ketone, and the solvent was permitted to evaporate. The same lacquer was applied to a finger tip before the latter was covered with a layer of adhesive paste of the following composition:

Parts by weight Polymethyl methacrylate 20 Methyl methacrylate 27.2 N,N-dimethyl-p-toluidine 0.55 Dioctylphthalate 2.5 Titanium dioxide 0.1 Cadmium red 0.05 Thymol 0.03

An amount of the paste about equal to the volume of a small pea was placed on the center of the coated natural nail, and was flattened by the superimposed coated nail blank which was applied under fairly strong manual pressure. The paste filled the space between the natural nail and the blank, an excess was squeezed out around the edges of the nail blank, and was partly removed. The remaining excess paste was smoothed out to cover the excess of the nail.

Benzoyl peroxide or other peroxides alone cause relatively slow polymerization of methyl methacrylate at ordinary temperature, and are not always practical. Redox catalyst systems are preferred, and a system in which benzoyl peroxide is the oxidizing component and pure N,N-dirnethyl-p-toluidine is the reducing component has been found to combine particularly convenient properties. Other redox catalyst systems suitable for inducing polymerization of acrylic monomers are known and may be employed to perform their conventional functions in this invention.

Acrylic bonding agents are preferred, particularly when combined with artificial nail blanks of the same or closely related material, but bonding agents based on polyesters, polycarbonates, or copolymers of acrylic monomers with' each other or with the monomeric constituents of the polyesters or the polycarbonates may readily be formulated by those skilled in the art on the basis of the above teachings.

The advantages of a paste-like composition of polymerizable monomers with other ingredients for use in the forming of artificial finger and toe nails in conjunction with a second composition including a polymerization catalyst for the monomer have been set forth in detail in the copending application Ser. No. 382,570, of Gerd Sautter, Erich Mockesch, and Franz Gotz, filed on July 14, 1964.

The paste composition has a long shelf life as long as it does not make contact with an oxidizing catalyst or the oxidizing component of a redox polymerization catalyst system. It does not tend to spread on the digit in an uncontrolled manner so that undesired physiological effects of the unsaturated monomer on body tissues can be avoided. The same considerations apply to the reducing component of a redox catalyst system which is usually a tertiary amine present in an amount of 0.5 to 1% of the monomer, and which also may have strong physiological effects in contact wtih some body tissues.

The paste compositions listed above cure substantially completely within seven minutes after contact with the oxidizing component of the catalyst system. The time available for forming the artificial nail covering is thus limited, but amply sufficient in view of the simple method of application available with the two-component system of materials provided by this invention. The short curing time makes it also practical to dispense with the use of a protective lacquer between the adhesive paste and the nail or skin if reasonable care is taken to keep the paste away from open cuts or wounds.

The three-dimensional curvature of the nail blank employed, and the fact that the space between nail blank and digit surface is completely filled by the cured paste when the nail covering of the invention has been formed, is responsible to a substantial extent for the good mechanical strength of the covering, and also for its resistance to water and other liquids.

A close fit between the dimensions of the nail blank and those of the covered nail is not necessary, as is evident from the drawing. An oversized nail blank is readily trimmed prior to application. A small number of nail blank sizes thus fits all fingers or toes. Adhesive paste exposed by an undersized nail blank may be coated with catalyst-bearing lacquer to accelerate its curing.

As has been shown in the examples, coloring matter may be contained in the bonding agent as well as in the nail blank, and known pigments other than those specifically disclosed are obviously operative. The use of nacreous pigments is specifically contemplated to enhance the appearance of the nail blank and of those portions of the bonding agent which may become visible in the finished nail covering.

Various other modifications are contemplated and may obviously be resorted to by those skilled in the art without departing from the spirit and scope of the invention as hereinafter defined by the appended claims as only preferred embodiments thereof have been disclosed.

What is claimed is:

1. A set of materials for forming an artificial nail covering on a digit of a user comprising in combination:

(a) an elongated, thin, artificial nail blank of solid,

shape retaining, resilient material having an outer face and an inner face, said inner face being concave in the longitudinal median plane thereof and in a plurality of planes perpendicular to said median plane;

(b) an oxidizing catalyst secured to said inner face;

and

(c) bonding means for adhesively bonding said inner face to said digit, said bonding means being a pastelike adhesive mass substantially free of said catalyst and respsonsive to contact With said catalyst to cure and thereby to adhere to said inner face, said catalyst being free of said bonding means and contained in a dry layer.

2. A set as set forth in claim 1, wherein said bonding means includes a polymerizable synthetic organic monomer adapted to be polymerized at a temperature not exceeding 37 C. by contact With said catalyst.

3. A set as set forth in claim 2, wherein said monomer is a lower-alkyl methacrylate, said catalyst is an organic peroxide, and the oxidizing component of a redox catalyst system adapted to polymerize said lower-alkyl methacrylate, said bonding means further including the reducing component of said system dissolved in said monomer.

4. A set as set forth in claim 3, wherein said reducing component is N,N-dimethyl-p-toluidine.

5. A set as set forth in claim 2, wherein a major portion of said solid resilient material is a polymer of said monomer.

6. A set as set forth in claim 2, further comprising coloring matter substantially uniformly distributed in said material from one of said faces to the other face.

7. A set as set forth in claim 1, wherein said outer face is convex in each of said planes.

8. A set as set forth in claim 1, further comprising a lacquer essentially consisting of a volatile organic solvent and a film forming polymer, said oxidizing catalyst being dissolved in said lacquer.

9. A set as set forth in claim 1, wherein said inner face of said blank is arcuately concave in each of said planes.

References Cited UNITED STATES PATENTS 2,688,331 9/1954 Bogoslowsky 13273 2,941,535 6/1960 Lappe 132-73 3,157,912 11/1964 Lisczawka 13288.5

RAYMOND F. GUIDA, Primary Examiner G. L. McNEILL, Assistant Examiner 

